Sheet piler back stop



Aug. 14, 1962 T. A. SIGLOW 3,049,349

SHEET PILER BACK STOP Filed Oct. 11, 1960 2 Sheets-Sheet 1 IN VEN TOR.

77/400505 ,4. s/azan Bowmzh, Judim WW Arroewrs Aug. 14, 1962 T. A. SIGLOW SHEET FILER BACK STOP 2 Sheets-Sheet 2 Filed Oct. 11, 1960 j JINVENTOR.

7794400606 ,4. 5/6Zoh/ Wad/(M10524 United States Patent W 3,049,349 SIEET FILER BACK STQP Thaddeus A. Sigiow, New Castle, Pa., assignor to Blaw- Knox Company, Pittsburgh, Pa., a corporation of Delaware Filed Oct. 11, 1960, Ser. No. 62,022 7 Claims. (Cl. 271S9) This invention relates to piling apparatus for metal sheets, and more particularly to improved sheet stop devices for such apparatus.

In modern high production practices, in the manufacture of metal sheets and the like, such as tin plate, light gauge steel sheets and aluminum sheets, hereinfater for convenience referred to as sheets, the sheets issue from the processing equipment such as a shearing and classifying line at very high speeds. The sheets then must be assembled at commensurate speeds into compact and accurately formed stacks or piles for transportation to other processing equipment, storage or shipping.

In piling the sheets, however, several problems must be solved. In the resulting pile or stack of sheets all edges of the sheets must be accurately aligned and the sheets and their edges must be undamaged. Accurate alignment is necessary to permit the sheets to be banded or othewise packed for shipment and transported without damage to projecting edges. Alignment is also necessary to permit the sheets to be removed from the stack in subsequent processing by automatic equipment which might not Work properly with misaligned sheets. Damage to the edges must be avoided since it could render the sheets unusuable, or require costly corrective measures to restore them, and since it could cause scratching or other damage to adjacent sheets in the pile. The problem of forming such a stack is rendered more diflicult when, as indicated above, the sheets are discharged onto the piler at high speeds and in rapid succession. The stop device on the sheet piling apparatus must be such as to halt the rapidly moving sheet in a very short distance without damage to its leading edge or other edges and must aid in aligning the sheets transversely and longitudinally.

During the piling operation, the high kinetic energy of the sheet is dissipated by converting it into work produced by movement of the sheet a short distance against resistance provided by the stop device. Certain types of stop devices have embodied a stop member faced with a thick layer of resilient material which deflects or deforms initially under the impact to dissipate part of the kinetic energy; the remainder of the kinetic energy is absorbed by movement of the stop member as a whole against resistance provided by suitable means such as an air cylinder. After the sheet has been halted, the stop member returns to its initial position, thus serving to align the sheet longitudinally with other sheets in the pile. Prior devices of this type, however, have usually proven unsatisfactory when it was attempted to use the same apparatus for the piling of sheets of widely different sizes and weights.

Because of competitive conditions and :high capital costs of equipment, it is highly desirable that the piling apparatus be capable of piling sheets of widely varying widths, lengths, and weights. Prior stop devices have been deficient in piling sheets of such varying characteristics without damage to the edges of the sheets, because the inertia of the stop member is constant Whereas the kinetic energy and momentum of the sheets vary with the weight of the sheets and hence with their size, assuming a constant sheet delivery speed. Consequently, a stop member which will act to halt and align large sheets without damage often causes damage to the edges of small sheets, since the inertia of the stop member, which is low enough to permit shock absorbing movement of the stop member 3,049,349 Patented Aug. 14, 1962 when struck by a large sheet, may be too great to permit appreciable movement of the stop member when it is struck by a small sheet, this even though the resistance provided by the resisting means is adjusted to be substantially lower. When the stop member cannot move sufficiently, due to high inertia, the force at the leading edge of the sheet during the dissipation of the kinetic energy of the sheet may be so great that the sheet edge may be badly-damaged. This problem is accentuated at high speeds of delivery of the sheets to the piling apparatus.

The problem cannot be solved by making the stop member so small that its inertia is low enough to permit its movement when struck by the smallest sheet handled, since in such case the stop member Will be so narrow that the bearing width on the stop member is inadequate for the large sheets to be handled. Under these circumstances, the large sheets can be damaged due to large localized forces on their leading edges during the opera.- tion of halting the sheets by a narrow stop member.

It is also desirable that the stop members be of such widths that regardless of the Width of the sheet, the corners of the sheet do not contact the stop member, thus eliminating the possibility of a corner striking and being damaged by the stop member when the sheet traveling to the piling apparatus is slightly askew, as occasionally occurs.

An object of this invention, therefore, is to provide piling apparatus embodying a stop device which is free of the above disadvantages and which solves the above indicated problems. Another object is to provide such piling apparatus embodying a stop device which will operate satisfactorily with sheets of widely varying sizes. A further object is the provision of such apparatus which will operate at high speeds. Another object is the provision of such apparatus having a stop member adjustable to provide different inertias for sheets of different Weights or sizes. A further object of the invention is to provide such apparatus in which the stop member is adjustable so that the Width of the portion thereof contacted by the leading edges of the sheets may be increased for larger sheets and decreased for smaller sheets.

Further objects and advantages of the invention will become apparent from the following description of a preferred form thereof reference being made to the accompanying drawings in which:

FIGURE 1 is a somewhat diagrammatic longitudinal sectional view along line 1--1 of FIGURE 2, of a preferred form of sheet piling apparatus embodying the stop device of the present invention;

FIGURE 2 is a somewhat diagrammatic transverse sectional view along line 2-2 of FIGURE 1, of a portion of the apparatus of FIGURE 1, the pile of sheets being omitted for the sake of clarity;

FIGURE 3 is a plan to an enlarged scale of the stop device shown in FIGURES 1 and 2 with the central and side auxiliary stop members in operative position to engage yieldingly the leading edges of advancing sheets;

FIGURE 4 is a section taken along line 44 of FIG- URE 3, including a diagram of the air supply and control system for the cylinder; and

FIGURE 5 is a perspective of the stop device of FIG- URES 3 and 4, showing the aluxiliary side members raised to their inoperative positions.

As shown in FIGURE 1, the illustrated sheet piling apparatus comprises a pile elevator generally indicated by reference numeral 1, supporting a pile P formed of sheets S one of which is shown as being advanced onto the pile. Elevator 1 is adapted to be raised to a sheet piling position as shown in full lines and to be lowered to a pile discharge position as shown in broken lines in FIGURE 1. The apparatus also includes a stacking member generally indicated by reference numeral 2, comprising a stop device 3 embodying the invention and suitable side and end guide members to aid in aligning the sheets. This stacking member is supported in a fixed position above the uppermost position of elevator 1. The apparatus of FIGURE 1 also includes a sheet discharge conveyor 4 which discharges the sheets S onto the piling apparatus where they are formed into the pile P.

The elevator 1 comprises a frame made up of side members 11 and cross members 12 and 13. The frame 10 is fixed to and supported on two piston rods 14 of hydraulic cylinders 15 disposed in a pit in the fioor F; by this means the frame the frame 10 may be raised or lowered as described below. The frame 10 supports cross members 16 on which are mounted bearings 17 carrying several shafts 13 which extend longitudinally of the apparatus. Rollers 19 are rigidly mounted on each of the several shafts 18, and the shafts and rollers are adapted to be rotated as required in unison by motor 21 through suitable driving means 22 shown as made up of gears and chains. Bolsters 23 supported transversely of the rollers 19, are preferably provided to support the pile of sheets P.

As the height of the pile of sheets P increases due to the stacking of sheets on the top of the pile, the elevator is gradually lowered, suitable control means, not shown, and forming no part of the invention, being provided for this purpose. When the desired pile height has been reached, which is limited by the necessity for clearing the under parts of stacking member 2, the elevator 1 is lowered until the tops of its rollers 19 are in line with the tops of the rollers 24 of a take-off conveyor mounted on the floor F, as shown in FIGURE 1. The motor 21 is then operated to rotate the rollers 19 and move the bolsters carrying the pile P onto the rollers 24 of the take-off conveyor, from which the pile P can be subsequently removed.

The stacking member 2, as shown in FIGURES 1 and 2, comprises longitudinally extending side members 31 connected to cross members 32. Longitudinally extending side guides 33, adapted to be adjustably moved transversely of stacking member 2 and of the sheets to handle different sheet widths, serve to guide the sheets transversely as they are piled on the apparatus. The adjustment is made for each width of sheet to be handle by rotatable cross shafts 34 threaded in bosses 35 fixed near the ends of the guides 33; threaded shafts 34 are rotated through suitable bevel gears 36 by shafts 37 extending longitudinally on the sides of the stacking member 2. Such shafts may be rotated by suitable power or manual means, not shown.

The apparatus thus far described, although preferable, is but one type of piling apparatus in connection with which the stop device 3 of the invention may be employed.

The stop device generally indicated by reference character 3 comprises a transverse frame member 40 which is fixed to slide members 41 slidably mounted on guides 42 secured to the tops of side members 31 of stacking member 2. At each end, member 49 carries a downwardly extending bracket 43 in which is threaded a lead screw 44 rotatably mounted adjacent each side member 31 of stacking member 2; by rotation in unison of the lead screws 44 the stop device 3 can be moved longitudinally of stacking member 2 to adjust it to handle sheets S of different lengths. Suitable manually or power actuated means, not shown, are provided to rotate the lead screws. A fixed transverse guide member 45 is mounted between the side rails 31 of stacking member 2 at its end remote from stop device 3, to locate the trailing edges of the sheets S. The sheets S are advanced at high speed and in rapid succession into the piling apparatus by power-driven rollers 46 and guide rollers 47 of feed table 4.

The illustrated stop device 3, as shown in FIGURES aasao 2 to 5, comprises a central stop member 51 which is pivotally supported near its upper end from the central portion of transverse member 40. Stop member 51 includes a rear supporting plate 52 to the rear upper portion of which are fixed two sets of spaced lugs 53 pivotally mounted on a shaft 54 supported on and extending parallel to the top of member 40 and hence transversely of the apparatus. Shaft 54 is rotatably supported in lugs 55, 56 and 56 fixed to the top of member 40, and is held against endwise movement by collars 57 fixed to the shaft and bearing against the lugs 56 The plate 52 is located against movement endwise of the shaft 54 by contact of its lugs 53 with the lugs on the member 40. Preferably the surface of the plate 52 facing the pile of sheets carries a thick pad-like member 58 formed of resilient material, such as rubber or the like, which deforms when struck by the leading edge of each moving sheet S traveling into the piling apparatus, thus absorbing a portion of the kinetic energy of the sheet and aiding in preventing damage to its leading edge. The stop member 51 as a whole is able to yield under the impact of the sheets S because of the pivotal mounting mentioned above. The extent of movement of the member under impact is controled by engagement of the rear of plate 52 against the piston rod 59 of an air cylinder 60 rigidly supported from member 40, as by bracket 62. Air pressure of adjustable predetermined magnitude is maintained in the cylinder by means to be later described, to permit limited pivotal movement of the stop member 51 against a predetermined resistance when it is struck by a sheet.

The illustrated stop device 3 embodies an auxiliary stop member 63 at each side of central stop member 51. Each auxiliary stop member 63 comprises a plate 64 having fixed to the upper portion of its rear side spaced lugs 65 which are rigidly secured by set screws 66 to the shaft 54. The side of each plate 64 facing the sheet S is provided with a pad 67 formed of resilient material like that of pad 58, and of such thickness that when the members 63 are in operative position the outer surfaces of the pads 67 lie substantially in alignment with the outer surface of pad 58; when the surfaces of the stop members are flat, as in the illustrated embodiment, they lie substantially in the same plane when in operative position.

Each of the auxiliary stop members 63 may be swung up and back to an inoperative position where it cannot be engaged by the edges of sheets S being delivered to the piling apparatus, as shown in FIGURE 5. In the illustrated embodiment, at each side of the apparatus there is a handle 68 which is secured to the shaft 54 to which the stop members 63 are fixed; the stop members may be simultaneously raised from or lowered to operative positions by rotating shaft 54 by means of either or both handles. Suitable means may he provided to lock the auxiliary stop members 63 in their inoperative position; such means may take the form of a spring-pressed pin 69 in the base of each handle 68, the end of the pin is adapted to engage a suitable hole in the adjacent lug 56 When the auxiliary stop members 63 are swung downwardly into their operative positions with the working faces of their pads 67 lying in substantially the same plane as the working face of pad 58 of central stop member 51, the plate 64 of each stop member 63 bears against the plate 52 of central stop member 51; this is accomplished by the extending portion 71 on each side edge of plate 52 of the central stop member, which project beyond the pad 51 and the rear portions 72 of the side edges of the plates 64. Thus the auxiliary stop members 63 are supported against the impact of the sheets by the central stop member 51.

It is to be noted that the pivot axis around which all stop members swing, i.e. the axis of shaft 54, is offset rearwardly from the rear plate members of all stop members and from the centers of gravity of such stop members when they are in their operative positions. Consequently, the central stop member 51 at all times has a r r tendency to swing back against the piston rod 59 of cylinder 6,0, which backward swing is resisted by the air pressure in the cylinder; and the auxiliary stop members, when in their operative positions, have a tendency to swing back so that they are at all times bearing against the central stop member as indicated above.

The means for controlling the pressure in the air cylinder 60 is diagrammatically shown in FIGURE 4. It comprises a conduit 73 leading froma suitable source of air under pressure to the air cylinder 60, a regulator valve 74 of conventional design in such line, a check valve 75 in such line, a safety relief valve 76 in the line, a bleeder valve 77 connected to the line between the valves 75 and 76, and a vent 78 connected to the low pressure side of the cylinder. In operation, air at a pressure determined by regulator valve 74 is admitted to the air cylinder 60, and is trapped in the cylinder by check valve 75. The air pressure in the cylinder will rise due to compression when the sheets S strike the stop member and the stop member is swung back. Thus, the resistance offered by the cylinder increases directly with the distance that the stop member is swung back under the impact of the sheets, and the air under pressure promptly returns the stop member to its original, vertical position after each impact so that the front edges of the sheets are accurately aligned. Safety relief valve 76 exhausts air if the pressure rises above a predetermined amount for which the valve is set. For any particular combination of piling speed and sheet weight, an optimum air cylinder pressure exists which can be readily determined after slight eX- perience. If the pressure in the air cylinder 60 is to be increased, this can be readily accomplished by adjusting regulator valve 74. If it should be desired to decrease the pressure in cylinder 60, the regulator valve 74 can be so adjusted and the higher pressure trapped in the cylinder exhausted by opening bleeder valve 77.

The operation of the illustrated apparatus is described below. When the heaviest sheets for which the apparatus is designed are to handled, i.e. those of maximum length and width, the auxiliary stop members 63 are swung down into their operative positions, so that their shoulders v72 contact the projecting shoulder 71 at the edges of the central stop member 51, to form a composite stop member of maximum width. The air pressure in cylinder 60 is adjusted to the optimum amount as described above. The elevator member 1, with bolsters 23 on its rollers 19, is raised to its extreme elevated position and the sheets are advanced at high speed by the rollers 46 over the rollers 47 into the piling apparatus. The sheets strike the pad members 58 and 67 of stop members 51 and 63.

Part of the kinetic energy of each sheet is dissipated in the resilient deformation of such pad members, and the remainder is absorbed by the resistance of the stop members as they are moved backward as a unit by the sheet against the resistance provided by the air pressure in the cylinder 60. The action as a unit is facilitated since the auxiliary stop members both bear against the main central stop member 51. When the sheet is brought to a halt, the air pressure in the cylinder 60 moves the central stop member 51 and the auxiliary side stop member 63 bearing against it forward to their original position, thus moving the top sheet longitudinally in the pile to a position in which it bears against the stationary guide member 45, thus aligning the sheet endwise. This sheet is aligned transversely by the side members 33 as it is halted. Since sheets of maximum width are being handled, the inertia of the composite stop member made up of the three step members is not excessive and the composite stop member can move rearwardly to absorb the sheet impact without damaging the edges of the sheet. As the height of the pile of sheets increases, the elevator 1 is gradually lowered so that the top of the pile is always in the position to permit the sheet being delivered to be most effectively acted upon by the stop device 3 and the side and end guide members. When a pile or stack of the desired height has been formed within the design limitation of the apparatus, the lift member 1 is lowered as indicated above to permit the stack to be moved to the take-off conveyor rollers 24.

When substantially lighter sheets, such as those which are narrower, are to be piled, the auxiliary stop members 63 are swung upwardly to their inoperative positions and locked in place, and only the central stop member 51 is employed to halt the sheets. If desirable or necessary, the air pressure in the air cylinder 60 can be lowered to decrease the resistance provided by stop member 51. Since the auxiliary stop members are swung to their inoperative positions, the inertia of the stop member being employed to halt the sheets is greatly reduced, thus eliminating the possibilities of damage to the leading edges of the sheets.

By proper design and manipulation of the stop members, it is also possible to operate the piling apparatus so that the stop member being used to halt the sheets is always narrower than the sheet being piled, even though narrow sheets are being piled. Consequently, even if the sheet is delivered to and strikes the stop member while it is slightly askew, there is no possibility of damage to the corners of the sheets since they do not strike the stop member.

Although in the illustrated apparatus three stop members are shown, it is apparent that a different number, including a greater number of stop members may be employed, depending on the requirements of the piling ap paratus and the widths and lengths of the sheets being handled.

The present invention therefore provides piling apparatus embodying a stop device in which the width of the stop member engaged by the sheets can be Varied or adjusted and in which the inertia of the stop member engaged by the sheets may be varied or adjusted. These features, in combination with the preferable adjustability of the air pressure in the air cylinder, make possible piling apparatus adapted to handle a wide range of sizes, widths and weights of sheets at extremely high speeds with substantially complete elimination of damage to the leading edges of the sheets from the stop members. These advantageous features, moreover, can be obtained at low costs due to the simple design and construction of the stop device of the invention.

Those skilled in the art will appreciate that the invention may be adapted to other types of piling apparatus than that illustrated, and that various changes and modifications can be made in the invention without departing from the spirit and scope thereof. The essential characteristics of the invention are defined in the appended claims.

I claim:

1. A stop device for halting advancing sheets to pile them comprising a main stop member having a forwardly facing working face adapted for yielding engagement with the leading edges of advancing sheets, said stop member being movable generally parallel to the direction of travel of said sheets; means for yieldingly urging said stop member toward a position in which it engages said advancing sheets and for yieldingly resisting motion of said stop member in the general direction of travel of said sheets; and an auxiliary stop member having a forwardly facing Working face adapted for engagement with the leading edges of said advancing sheets when said stop member is in its sheet-engaging position, said stop member being pivotally supported about an axis which is offset rearwardly from the working face of said stop member and from the center of gravity of said stop member when it is in sheet-engaging position, said auxiliary stop member being capable of being suspended from its pivot axis in a position in which it engages and is urged forwardly in sheet-engaging position by said main stop member while it is in sheet-engaging position and l the working faces of said main stop member and said auxiliary stop member form parts of substantially the same surface, said auxiliary stop member also being capable of being swung forwardly and upwardly about its pivot axis to an inoperative position Where it cannot engage advancing sheets.

2. A stop device for halting advancing metal sheets to pile them comprising a main movably mounted stop member having a working face positioned to be struck by the leading edges of advancing sheets, means for yieldingly resisting movement of said main stop memher in the direction of advance of said sheets, at least one auxiliary stop member having a working face adapted to be struck by the leading edges of advancing sheets, said auxiliary stop member being mounted to be selectively disposed in an inoperative position out of the path of said sheets and in an operative position in which its working face is disposed in substantial alignment with the working face of said main stop member, and means connecting said stop members whereby said stop members move as a unit in the direction of advance of said sheets when the auxiliary stop member is struck by an advancing sheet.

3. A stop device for halting advancing sheets to pile them, comprising a support; a main stop member having a forwardly facing working face adapted for yielding engagement with the leading edges of advancing sheets, said stop member being pivotally suspended from said support about an axis which is transverse to the direction of travel of said advancing sheets and is offset rearwardly from the working face of said stop member and from the center of gravity of said stop member when it is in sheet-engaging position, whereby said stop member tends to swing rearwardly by gravity; means for yieldingly urging said stop member forward to sheetengaging position and for yieldingly resisting movement in the general direction of travel of said advancing sheets; and, located at each side of said main stop member, an auxiliary stop member having a forwardly facing working face adapted for engagement with the leading edges of said advancing sheets when said auxiliary stop member is in sheet-engaging position, said stop member being pivotally supported from said support about an axis which is offset rearwardly from the working face of said stop member and from the center of gravity of I said stop member when it is in sheet-engaging position, said auxiliary stop member being capable of being suspended from its pivot axis in a position in which it engages and is urged forwardly in sheet-engaging position by said main stop member while it is in its sheet-engaging position and the Working faces of said main stop member and said auxiliary stop member form parts of substantially the same surface, each of said auxiliary stop members also being capable of being swung forwardly and upwardly about its pivot axis to an inoperative position where it cannot engage advancing sheets.

4. A stop device for halting advancing sheets to pile them, comprising a support; a main stop member having a forwardly facing working face adapted for yielding engagement with the leading edges of advancing sheets, said stop member being pivotally suspended from said support about an axis which is transverse to the direction of travel of said advancing sheets and is offset rearwardly from the working face of said stop member and from the center of gravity of said stop member when it is in sheet-engaging position, whereby said stop member tends to swing rearwardly by gravity; means for yieldingly urging such a stop member forward to sheetengaging position and for yieldingly resisting movement of said stop member in the general direction of travel of said advancing sheets; an auxiliary stop member having a forwardly facing working face adapted for engagement with the leading edges of said advancing sheets when said stop member is in its sheet-engaging position, said stop member being pivotally supported from said support about an axis which is substantially coincident with the pivot axis of said main stop member and which is offset rearwardly from the working face of said auxiliary stop member and from the center of gravity of said auxiliary stop member when it is in sheet-engaging position, said auxiliary stop member being capable of being suspended from its pivot axis in a position in which it engages and is urged forwardly in sheet-engaging position by said main stop member While it is in its sheetengaging position and the working faces of said main stop member and said auxiliary stop member form parts of substantially the same surface, so that said main and auxiliary stop members swingingly move as a unit when said stop members are struck by an advancing sheet, said stop auxiliary member also being capable of being moved forwardly and upwardly about its pivot axis to an inoperative position where it cannot engage advancing sheets.

5. A stop device for halting advancing sheets to pile them, comprising a support; a main stop member having a forwardly facing working face adapted for yielding engagement with the leading edges of advancing sheets, said stop member being pivotally suspended from said support about an axis which is transverse to the direction of travel of said advancing sheets and is offset rearwardly from the working face of said stop member and from the center of gravity of said stop member when it is in sheet-engaging position, whereby said stop member tends to swing rearwardly by gravity; means for yieldingly urging said stop member forward to sheet-engaging position and for yieldingly resisting movement of said stop member in the general direction of advance of said sheets; and, located at each side of said main stop member, an auxiliary stop member having a forwardly facing working face adapted for engagement with the leading edges of said advancing sheets when said auxiliary stop member is in sheet-engaging position, said stop member being pivotally supported from said support about an axis which is substantially coincident with the pivot axis of said main stop member and which is olfset rearwardly from the working face of said auxiliary stop member and from the center of gravity of said auxiliary stop member when it is in sheet-engaging position, said auxiliary stop member being capable of being suspended from its pivot axis in a position in which it engages and is urged forwardly in sheet-engaging position by said main stop member While it is in its sheet-engaging position and the working faces of said main stop member and said auxiliary stop member form parts of substantially the same surface so that said main stop member and both of said auxiliary stop members can swingingly move as a unit when said stop members are struck by an advancing sheet, each of said auxiliary stop members also being capable of being swung forwardly and upwardly about its pivot axis to an inoperative position where it cannot engage advancing sheets.

6. A stop device for halting advancing sheets to pile them, comprising a support; a main stop member having a forwardly facing working face adapted for yielding engagement with the leading edges of advancing sheets, said stop member being pivotally suspended from said support about an axis which extends transversely to the direction of travel of said advancing sheets, said stop member having extending in a direction transverse to its pivot axis an edge portion with a forwardly facing bearing surface; means for yieldingly urging said stop member forward to sheet-engaging position and for yieldingly resisting movement in the general direction of travel of said advancing sheets; and an auxiliary stop member having a forwardly facing working face adapted for engagement with the leading edges of said advancing sheets when said stop member is in its sheet-engaging position, said stop member being pivotally supported from said support about an axis which is substantially coincident with the pivot axis of said main stop member, said auxiliary stop member having extending in a direction transverse to its pivot axis an edge portion with a rearwardly facing bearing surface, said stop member being capable of being suspended from its pivot axis in a position in which its edge portion overlaps the edge portion of said main stop member with the bearing surfaces of said edge portions in contact to cause said auxiliary stop member to be urged forwardly in sheet-engaging position by said main stop member while it is in its sheet-engaging position, so that said main and auxiliary stop members can swingingly move as a unit when said stop members are struck by an advancing sheet, said auxiliary stop member also being capable of being swung forwardly and upwardly about its pivot axis to an inoperative position where it cannot engage advancing sheets.

7. A stop device for halting advancing sheets to pile them, comprising a support; a main stop member having a forwardly facing working face adapted for yielding engagement with the leading edges of advancing sheets, said stop member being pivotally suspended from said support about an axis which extends transversely to the direction of travel of said advancing sheets and is offset rearwardly from the working face of said stop member and from the center of gravity of said stop member when it is in sheet-engaging position, whereby said stop member tends to swing rearwardly by gravity, said stop member having extending in directions transversely to its pivot axis two side edge portions with forwardly facing bearing surfaces; means for yieldingly urging said main stop member forward to sheet-engaging position and for yieldingly resisting movement of said stop member in the general direction of travel of said advancing sheets; and, located at each side of said main stop member, an auxil- 10 ia-ry stop member having a forwardly facing working face adapted for engagement with the leading edges of said advancing sheets when said auxiliary stop member is in sheet-engaging position, said stop member being pivotally supported from said support about an axis which is substantially coincident with the pivot axis of said main stop member and which is offset rearwardly from the working face of said auxiliary stop member and from the center of gravity of said auxilira-y stop member when it is in sheet-engaging position, each of said auxiliary stop members having extending in a direction transverse to its pivot axis an edge portion adjacent to said main stop member and having a rearwardly facing bearing surface, each of said auxiliary members being capable of being suspended from its pivot axis in a position where its edge portion overlaps the adjacent edge portion of said main stop member with their hearing surfaces in contact to cause said auxiliary member to be urged forwardly in sheet-engaging position by said main stop member while it is in its sheet-engaging position, so that said main stop member and both of said auxilia-ry stop members can swingingly move as a unit when said stop members are struck by an advancing sheet, each of said auxiliary stop members being capable of being swung forwardly and upwardly about its pivot axis to an inoperative position where it cannot engage advancing sheets.

References Cited in the tile of this patent UNITED STATES PATENTS 2,626,800 Martin Ian. 27, 1953 2,882,048 Smith Apr. 14, 1959 2,957,691 Williams Oct. 25, 1960 

